Lionfish have been migrating (迁徙) south for years. They were first caught in the Gulf of Mexico, likely released from the aquarium trade, in 1985, and quickly expanded into the US East Coast and the Caribbean. They reached South American coastlines around 2010.

But the species stopped around Venezuela and Trinidad and Tobago. For 10 years, freshwater flowing from the Amazon River into the Atlantic and a gathering of currents acted as geographic (地理的) barriers, stopping the fish from continuing south. But around 2020, lionfish began slip-ping under the barrier and heading south.

Now, dozens of lionfish have been spotted along 150 miles of Brazil’s coastline, according to a new study in Frontiers in Marine Science. Between March and May, when the water was clear enough to track the fish, researchers and fishers documented 72 individuals there, which suggests they have likely established new, successful populations.

Since March 2022, lionfish already managed to cover 700 kilometers of coastline, says Marcelo Soares, a marine ecologist and lead author of the new study. He also reported the number of individuals is now above 300.

For many scientists, the question wasn’t whether the fish species would continue moving south, but when. “We knew once they made it through the barrier at the Amazon, they would spread like fire,” says Osmar Luiz, an aquatic ecologist at Australia’s Charles Darwin University.

While efforts to fully get rid of lionfish may be useless, efforts to reduce their populations help limit damage to native species. Luiz says that the next important step is to track lionfish as they move and try to prevent them from establishing new populations. For the native species of Brazil, this fight is a matter of survival, Luiz says.

Sagarika Sriram was just 10 years old when she started reading newspaper stories about a planet in trouble. One story was about a whale that washed ashore after an oil spill (泄露). Another was about turtles found with plastic in their stomachs. Sagarika knew she needed to do something. So she joined a group that organized cleanup campaigns in Dubai, her home city, in the United Arab Emirates. The experience, she says, “helped me understand what an individual (个人的) can do and how I can really make a difference.”

But individual power is greatest on a larger scale (程度). So in 2016, Sagarika created Kids for a Better World. It’s a digital platform that has brought together nearly 10,000 youths from all over the world. Its goal is to fight climate change.

Sagarika is now 16. She’s part of a growing body of young climate activists who are working together in the name of a cleaner, healthier future. “We’re the generation that is going to face the consequences if the climate crisis is not dealt with,” Sagarika says. She believes even small individual actions can create a “ripple effect”, promoting development in the right direction. “Change can be created on large levels with even small actions. ” she says.

Kids for a Better World is for people ages 8 to 16. The platform teaches them about what they can do at home and in their community to reverse (反转) climate change. They can grow food or plant trees. They can collect recyclables and avoid using plastic bags. These are lessons Sagarika wants schools to teach. “This is the information which can help change our future.” she says.

Growing up in a large desert city has made Sagarika even more aware of the need for action. Her city faces risks from rising temperatures and shrinking water supplies. She believes youth advocacy (倡议) can bring attention to these environmental challenges.

Even if she’s all about small actions, Sagarika has big plans. She’d like to study at Stanford University, in California. And while she’s there, she’ll continue being an activist and running Kids for a Better World. Sagarika hopes to inspire others to fight for a greener planet, as others have inspired her. “We’re creating our own system of inspirational change-makers.” she says.

The Salton Sea in California is actually a salty inland lake. The level of salt in the lake’s water—what scientists call its salinity—has been increasing steadily for years because the lake’s water is evaporating (蒸发) faster than it is being replaced by rainfall or rivers. If this continues, the lake’s water will soon become so salty that the lake will be unable to support fish and bird populations. The lake would then become a dead zone. Fortunately, there are several ways to change this situation that is threatening the lake’s health.

One choice is direct removal of salt from the lake’s water in special machines. Water from the lake would be forced into the machine and heated. This would cause the water to evaporate into steam, while salt and other materials dissolved (溶解) in the water would be left behind. The steam would then be cooled down and returned to the lake as salt-free water. Gradually, the high salt levels would be reduced and the lake’s overall health would be restored.

Another possible solution is to make the salt level weaker in the lake with water from the ocean. Since water in the Pacific Ocean is 20 percent less salty than water in the lake, bringing ocean water into the lake would decrease the lake’s salinity. The ocean water could be delivered through pipelines or canals.

Yet another solution would be to control the lake’s salinity by building walls to divide the lake into several parts. In the smaller parts, salinity would be allowed to increase. However, in the main and largest part, salinity would be reduced and controlled by directing all the freshwater from small rivers in the area to flow into that main part of the lake.